1. Field of the Invention
This invention relates to a speed changeable gear drive apparatus, more particularly to a speed changeable gear drive apparatus for transmitting a drive of an output shaft of an electrically powered motor to drive a wheeled vehicle.
2. Description of the Related Art
A conventional motorcar includes a mechanical drive apparatus for transmitting a drive of an output shaft of an electrically powered motor to a differential gear device to drive the wheel axles of the motorcar. Moreover, a motor frequency changer is provided to control the rotary speed of the output shaft of the electrically powered motor. However, the motor frequency changer is expensive and is liable to cause damage after a long term of use.